ClickHouse/dbms/src/Functions/isValidUTF8.cpp

#include <DataTypes/DataTypeString.h>
#include <Functions/FunctionFactory.h>
#include <Functions/FunctionStringOrArrayToT.h>

#include <cstring>

#ifdef __SSE4_1__
#    include <emmintrin.h>
#    include <smmintrin.h>
#    include <tmmintrin.h>
#endif

namespace DB
{
struct ValidUTF8Impl
{
    /*
 * inspired by https://github.com/cyb70289/utf8/
 * http://www.unicode.org/versions/Unicode6.0.0/ch03.pdf - page 94
 *
 * Table 3-7. Well-Formed UTF-8 Byte Sequences
 *
 * +--------------------+------------+-------------+------------+-------------+
 * | Code Points        | First Byte | Second Byte | Third Byte | Fourth Byte |
 * +--------------------+------------+-------------+------------+-------------+
 * | U+0000..U+007F     | 00..7F     |             |            |             |
 * +--------------------+------------+-------------+------------+-------------+
 * | U+0080..U+07FF     | C2..DF     | 80..BF      |            |             |
 * +--------------------+------------+-------------+------------+-------------+
 * | U+0800..U+0FFF     | E0         | A0..BF      | 80..BF     |             |
 * +--------------------+------------+-------------+------------+-------------+
 * | U+1000..U+CFFF     | E1..EC     | 80..BF      | 80..BF     |             |
 * +--------------------+------------+-------------+------------+-------------+
 * | U+D000..U+D7FF     | ED         | 80..9F      | 80..BF     |             |
 * +--------------------+------------+-------------+------------+-------------+
 * | U+E000..U+FFFF     | EE..EF     | 80..BF      | 80..BF     |             |
 * +--------------------+------------+-------------+------------+-------------+
 * | U+10000..U+3FFFF   | F0         | 90..BF      | 80..BF     | 80..BF      |
 * +--------------------+------------+-------------+------------+-------------+
 * | U+40000..U+FFFFF   | F1..F3     | 80..BF      | 80..BF     | 80..BF      |
 * +--------------------+------------+-------------+------------+-------------+
 * | U+100000..U+10FFFF | F4         | 80..8F      | 80..BF     | 80..BF      |
 * +--------------------+------------+-------------+------------+-------------+
 */

    static inline UInt8 isValidUTF8Naive(const UInt8 * data, UInt64 len)
    {
        while (len)
        {
            int bytes;
            const UInt8 byte1 = data[0];
            /* 00..7F */
            if (byte1 <= 0x7F)
            {
                bytes = 1;
            }
            /* C2..DF, 80..BF */
            else if (len >= 2 && byte1 >= 0xC2 && byte1 <= 0xDF && static_cast<Int8>(data[1]) <= static_cast<Int8>(0xBF))
            {
                bytes = 2;
            }
            else if (len >= 3)
            {
                const UInt8 byte2 = data[1];
                bool byte2_ok = static_cast<Int8>(byte2) <= static_cast<Int8>(0xBF);
                bool byte3_ok = static_cast<Int8>(data[2]) <= static_cast<Int8>(0xBF);

                if (byte2_ok && byte3_ok &&
                    /* E0, A0..BF, 80..BF */
                    ((byte1 == 0xE0 && byte2 >= 0xA0) ||
                     /* E1..EC, 80..BF, 80..BF */
                     (byte1 >= 0xE1 && byte1 <= 0xEC) ||
                     /* ED, 80..9F, 80..BF */
                     (byte1 == 0xED && byte2 <= 0x9F) ||
                     /* EE..EF, 80..BF, 80..BF */
                     (byte1 >= 0xEE && byte1 <= 0xEF)))
                {
                    bytes = 3;
                }
                else if (len >= 4)
                {
                    bool byte4_ok = static_cast<Int8>(data[3]) <= static_cast<Int8>(0xBF);
                    if (byte2_ok && byte3_ok && byte4_ok &&
                        /* F0, 90..BF, 80..BF, 80..BF */
                        ((byte1 == 0xF0 && byte2 >= 0x90) ||
                         /* F1..F3, 80..BF, 80..BF, 80..BF */
                         (byte1 >= 0xF1 && byte1 <= 0xF3) ||
                         /* F4, 80..8F, 80..BF, 80..BF */
                         (byte1 == 0xF4 && byte2 <= 0x8F)))
                    {
                        bytes = 4;
                    }
                    else
                    {
                        return false;
                    }
                }
                else
                {
                    return false;
                }
            }
            else
            {
                return false;
            }
            len -= bytes;
            data += bytes;
        }
        return true;
    }

#ifndef __SSE4_1__
    static inline UInt8 isValidUTF8(const UInt8 * data, UInt64 len) { return isValidUTF8Naive(data, len); }
#else
    static inline UInt8 isValidUTF8(const UInt8 * data, UInt64 len)
    {
        /*
        * Map high nibble of "First Byte" to legal character length minus 1
        * 0x00 ~ 0xBF --> 0
        * 0xC0 ~ 0xDF --> 1
        * 0xE0 ~ 0xEF --> 2
        * 0xF0 ~ 0xFF --> 3
        */
        const __m128i first_len_tbl = _mm_setr_epi8(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 3);

        /* Map "First Byte" to 8-th item of range table (0xC2 ~ 0xF4) */
        const __m128i first_range_tbl = _mm_setr_epi8(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8);

        /*
        * Range table, map range index to min and max values
        */
        const __m128i range_min_tbl
            = _mm_setr_epi8(0x00, 0x80, 0x80, 0x80, 0xA0, 0x80, 0x90, 0x80, 0xC2, 0x7F, 0x7F, 0x7F, 0x7F, 0x7F, 0x7F, 0x7F);

        const __m128i range_max_tbl
            = _mm_setr_epi8(0x7F, 0xBF, 0xBF, 0xBF, 0xBF, 0x9F, 0xBF, 0x8F, 0xF4, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80);

        /*
        * Tables for fast handling of four special First Bytes(E0,ED,F0,F4), after
        * which the Second Byte are not 80~BF. It contains "range index adjustment".
        * +------------+---------------+------------------+----------------+
        * | First Byte | original range| range adjustment | adjusted range |
        * +------------+---------------+------------------+----------------+
        * | E0         | 2             | 2                | 4              |
        * +------------+---------------+------------------+----------------+
        * | ED         | 2             | 3                | 5              |
        * +------------+---------------+------------------+----------------+
        * | F0         | 3             | 3                | 6              |
        * +------------+---------------+------------------+----------------+
        * | F4         | 4             | 4                | 8              |
        * +------------+---------------+------------------+----------------+
        */

        /* index1 -> E0, index14 -> ED */
        const __m128i df_ee_tbl = _mm_setr_epi8(0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0);

        /* index1 -> F0, index5 -> F4 */
        const __m128i ef_fe_tbl = _mm_setr_epi8(0, 3, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

        __m128i prev_input = _mm_set1_epi8(0);
        __m128i prev_first_len = _mm_set1_epi8(0);
        __m128i error = _mm_set1_epi8(0);

        auto checkPacked = [&](__m128i input) noexcept
        {
            /* high_nibbles = input >> 4 */
            const __m128i high_nibbles = _mm_and_si128(_mm_srli_epi16(input, 4), _mm_set1_epi8(0x0F));

            /* first_len = legal character length minus 1 */
            /* 0 for 00~7F, 1 for C0~DF, 2 for E0~EF, 3 for F0~FF */
            /* first_len = first_len_tbl[high_nibbles] */
            __m128i first_len = _mm_shuffle_epi8(first_len_tbl, high_nibbles);

            /* First Byte: set range index to 8 for bytes within 0xC0 ~ 0xFF */
            /* range = first_range_tbl[high_nibbles] */
            __m128i range = _mm_shuffle_epi8(first_range_tbl, high_nibbles);

            /* Second Byte: set range index to first_len */
            /* 0 for 00~7F, 1 for C0~DF, 2 for E0~EF, 3 for F0~FF */
            /* range |= (first_len, prev_first_len) << 1 byte */
            range = _mm_or_si128(range, _mm_alignr_epi8(first_len, prev_first_len, 15));

            /* Third Byte: set range index to saturate_sub(first_len, 1) */
            /* 0 for 00~7F, 0 for C0~DF, 1 for E0~EF, 2 for F0~FF */
            __m128i tmp1;
            __m128i tmp2;
            /* tmp1 = saturate_sub(first_len, 1) */
            tmp1 = _mm_subs_epu8(first_len, _mm_set1_epi8(1));
            /* tmp2 = saturate_sub(prev_first_len, 1) */
            tmp2 = _mm_subs_epu8(prev_first_len, _mm_set1_epi8(1));
            /* range |= (tmp1, tmp2) << 2 bytes */
            range = _mm_or_si128(range, _mm_alignr_epi8(tmp1, tmp2, 14));

            /* Fourth Byte: set range index to saturate_sub(first_len, 2) */
            /* 0 for 00~7F, 0 for C0~DF, 0 for E0~EF, 1 for F0~FF */
            /* tmp1 = saturate_sub(first_len, 2) */
            tmp1 = _mm_subs_epu8(first_len, _mm_set1_epi8(2));
            /* tmp2 = saturate_sub(prev_first_len, 2) */
            tmp2 = _mm_subs_epu8(prev_first_len, _mm_set1_epi8(2));
            /* range |= (tmp1, tmp2) << 3 bytes */
            range = _mm_or_si128(range, _mm_alignr_epi8(tmp1, tmp2, 13));

            /*
             * Now we have below range indices caluclated
             * Correct cases:
             * - 8 for C0~FF
             * - 3 for 1st byte after F0~FF
             * - 2 for 1st byte after E0~EF or 2nd byte after F0~FF
             * - 1 for 1st byte after C0~DF or 2nd byte after E0~EF or
             *         3rd byte after F0~FF
             * - 0 for others
             * Error cases:
             *   9,10,11 if non ascii First Byte overlaps
             *   E.g., F1 80 C2 90 --> 8 3 10 2, where 10 indicates error
             */

            /* Adjust Second Byte range for special First Bytes(E0,ED,F0,F4) */
            /* Overlaps lead to index 9~15, which are illegal in range table */
            __m128i shift1, pos, range2;
            /* shift1 = (input, prev_input) << 1 byte */
            shift1 = _mm_alignr_epi8(input, prev_input, 15);
            pos = _mm_sub_epi8(shift1, _mm_set1_epi8(0xEF));
            /*
             * shift1:  | EF  F0 ... FE | FF  00  ... ...  DE | DF  E0 ... EE |
             * pos:     | 0   1      15 | 16  17           239| 240 241    255|
             * pos-240: | 0   0      0  | 0   0            0  | 0   1      15 |
             * pos+112: | 112 113    127|       >= 128        |     >= 128    |
             */
            tmp1 = _mm_subs_epu8(pos, _mm_set1_epi8(240));
            range2 = _mm_shuffle_epi8(df_ee_tbl, tmp1);
            tmp2 = _mm_adds_epu8(pos, _mm_set1_epi8(112));
            range2 = _mm_add_epi8(range2, _mm_shuffle_epi8(ef_fe_tbl, tmp2));

            range = _mm_add_epi8(range, range2);

            /* Load min and max values per calculated range index */
            __m128i minv = _mm_shuffle_epi8(range_min_tbl, range);
            __m128i maxv = _mm_shuffle_epi8(range_max_tbl, range);

            /* Check value range */
            error = _mm_or_si128(error, _mm_cmplt_epi8(input, minv));
            error = _mm_or_si128(error, _mm_cmpgt_epi8(input, maxv));

            prev_input = input;
            prev_first_len = first_len;

            data += 16;
            len -= 16;
        };

        while (len >= 16)
            checkPacked(_mm_loadu_si128(reinterpret_cast<const __m128i *>(data)));

        if (len)
        {
            alignas(16) char buf[32];
            _mm_store_si128(reinterpret_cast<__m128i *>(buf), _mm_loadu_si128(reinterpret_cast<const __m128i *>(data)));
            memset(reinterpret_cast<char *>(&buf) + len, 0, 16);
            checkPacked(_mm_load_si128(reinterpret_cast<__m128i *>(buf)));
        }
        /* Reduce error vector, error_reduced = 0xFFFF if error == 0 */
        return _mm_movemask_epi8(_mm_cmpeq_epi8(error, _mm_set1_epi8(0))) == 0xFFFF;
    }
#endif

    static constexpr bool is_fixed_to_constant = false;

    static void vector(const ColumnString::Chars & data, const ColumnString::Offsets & offsets, PaddedPODArray<UInt8> & res)
    {
        size_t size = offsets.size();
        size_t prev_offset = 0;
        for (size_t i = 0; i < size; ++i)
        {
            res[i] = isValidUTF8(data.data() + prev_offset, offsets[i] - 1 - prev_offset);
            prev_offset = offsets[i];
        }
    }

    static void vector_fixed_to_constant(const ColumnString::Chars & /*data*/, size_t /*n*/, UInt8 & /*res*/) {}

    static void vector_fixed_to_vector(const ColumnString::Chars & data, size_t n, PaddedPODArray<UInt8> & res)
    {
        size_t size = data.size() / n;
        for (size_t i = 0; i < size; ++i)
            res[i] = isValidUTF8(data.data() + i * n, n);
    }

    static void array(const ColumnString::Offsets &, PaddedPODArray<UInt8> &)
    {
        throw Exception("Cannot apply function isValidUTF8 to Array argument", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
    }
};

struct NameValidUTF8
{
    static constexpr auto name = "isValidUTF8";
};
using FunctionValidUTF8 = FunctionStringOrArrayToT<ValidUTF8Impl, NameValidUTF8, UInt8>;

void registerFunctionValidUTF8(FunctionFactory & factory)
{
    factory.registerFunction<FunctionValidUTF8>();
}

}